1. Field of the Invention
The present invention relates to disk apparatuses and, in particular, to a disk apparatus that takes measures to prevent the degradation in the accuracy of the operation of optically processing a rotating disk surface using an optical pickup due to the vibration and therefore the change in the posture of a traverse as a movable member on which the optical pickup is mounted.
2. Description of the Related Art
FIG. 7 is a perspective outside view of a disk apparatus such as a DVD drive for optically processing a disk surface using an optical pickup for recording or reproduction.
In the disk apparatus shown in FIG. 7, a disk tray 2 is assembled ejectable and retractable in a chassis 1 as a fixed member called loader chassis, and a disk can be carried in and out of a set position where the optical pickup not shown in the drawing can perform optical processing by retracting and ejecting the disk tray 2.
FIG. 8 is a schematic cross-sectional view showing a state where a disk D carried in the set position is clamped by a clamp mechanism 3 that is assembled in the chassis, and FIG. 9 is a schematic cross-sectional view showing a state where the clamping state by the clamp mechanism 3 is released and the disk is carried out of the set position.
The clamp mechanism 3 shown in FIGS. 8 and 9 includes a turntable 31 connected directly to the rotation axis of a motor M and a clamper 32 provided on the beam part 12 of the chassis 1 in such a manner as to face the turntable 31. The motor M is provided on a rectangular frame-shaped movable member 4 on which the optical pickup not shown in the drawings is mounted. Appropriate portions of the movable member 4 such as the both end portions in the width direction at the base end portion (rear end portion) thereof are attached in a cantilever manner to the chassis 1 via elastic bodies 41 as cushion members made of rubber, the movable member 4 being movable vertically between an upper first position and a lower second position around the base end portion. Then, when the movable member 4 is in the first position as shown in FIG. 8, the turntable 31 with the disk D placed thereon comes close to the clamper 32 and the two components 31 and 32 cooperate with each other to hold the disk D therebetween, and further the optical pickup faces the disk surface. The optical processing on the disk surface using the optical pickup is performed by rotating the disk D together with the turntable 31 while the clamp mechanism 3 thus clamps the disk D. On the other hand, when the turntable 31 moves downward together with the optical pickup and the movable member 4 is retracted to the second position as shown in FIG. 9, a clearance for allowing passage of the disk therethrough is formed between the turntable 31 and the clamper 32, and the optical pickup is kept away from the disk surface. The disk can be carried in and out while the movable member 4 is thus moved from the first to second position. Then, if the movable member 4 is retracted from the first to second position, the clamp mechanism 3 performs an unclamping operation. The direction of carrying in and out the disk is indicated by the arrow R in FIG. 9.
A cam mechanism 5 is employed to move the movable member 4 between the first and second positions. The exemplary cam mechanism 5 shown in the drawings includes a shift lever 51 connected to the free end portion of the movable member 4 via elastic bodies 42 as cushion members made of rubber to exhibit a vibration damping effect and a cam main body 55 for allowing the movable member 4 to follow the up-and-down movement of the shift lever 51 and thereby to move between the first and second positions. More specifically, a protrusion 52 on the shift lever 51 is in slidable contact with the cam surface 56 of the cam main body 55. In the exemplary disk apparatus shown in the drawings, the cam main body 55 is constituted by a cam slider movable in the width direction of the chassis 1, and power for driving the cam main body 55 is to be transmitted through a gear 13. The cam surface 56 of the cam main body 55 is tilted so that when the reciprocating cam main body 55 slides in one direction for example, the shift lever 51 moves upward and the movable member 4 follows the upward movement to move from the second to first position, while when the cam main body 55 slides in the other direction, the shift lever 51 moves downward and the movable member 4 follows the downward movement to move from the first to second position.
The elastic bodies 41 and 42 employed in this disk apparatus have only elasticity capable of exhibiting an effect of absorbing vibrations due to the rotation of the motor M and the turntable 31 during optical processing using the optical pickup. Also, the elastic bodies 42, which are provided at the connection between the free end portion of the movable member 4 and the shift lever 51, have only elasticity deformable during the up-and-down movement of the shift lever 51 so that the shift lever 51 can be moved with respect to the free end portion of the movable member 4.
In such a disk apparatus as mentioned above in which the turntable 31 is rotated at about so-called double speed (3000 RPM) during optical processing using the optical pickup, the movable member 4 may employ a resin molded body for weight saving, and it has been known that no vibration causing operational performance problems can occur even if the thus lightened movable member 4 may be used.
However, it has recently been required to take measures so that no vibration causing operational performance problems can occur even if the rotation speed of the turntable 31 may be increased to about quad speed (6000 RPM) to increase the speed of optical processing using the optical pickup. Hence, in order to address such a requirement, the lightened movable member 4 formed of a resin molded body may be provided with a sheet metal weight of several tens of grams to limit vibration.
Meanwhile, there has conventionally been a proposal of installing an additional mass to cancel eccentric loading during disk rotation with focus on the fact that a centrifugal force due to such eccentric loading mainly causes vibration of the apparatus (refer to Japanese Patent Laid-Open Publication No. Hei 11-3582 for example). There has also been a proposal about measures for limiting horizontal vibration of a traverse base in an optical disk apparatus due to disk rotation by bringing a side shoe into contact with the traverse base (refer to Japanese Patent Laid-Open Publication No. 2002-8345 for example).
It has, however, been known that providing the movable member 4 with a weight exhibits an effect of limiting vibration, but at the same time, may lead to a situation where due to the clearance ensured between the protrusion 52 on the shift lever 51 and the cam surface 56 of the cam main body 55 and/or the elasticity of the elastic bodies 42, etc., the weight causes the free end portion of the movable member 4 to be displaced lower than its proper position when the movable member 4 is in the first position, which causes the optical pickup to be displaced from its proper position with respect to the disk D, resulting in a degradation in the accuracy of the optical processing. As for this, the proposals described in Japanese Patent Laid-Open Publication Nos. Hei 11-3582 and 2002-8345 cannot avoid such a situation.